1. Field of the Invention
The present invention relates generally to a deflection yoke apparatus to be mounted on the cathode ray tubes of television receivers or display apparatus.
2. Description of the Related Art
Generally, a deflection yoke apparatus comprises a horizontal deflection coil and a vertical deflection coil. Deflection coils are classified by a winding pattern into two types; saddle type coils which are wound saddle-shaped, and troidal type coils which are wound in a troidal form. A deflection yoke apparatus in which saddle type coils are used for each of horizontal deflection coil and vertical deflection coil is called a saddle-saddle type deflection yoke apparatus.
As shown in FIG. 13, a deflection yoke apparatus 30 has a hollow shape which gradually expands from the neck side toward the screen side. This deflection yoke apparatus 30 is designed to be inserted with its screen side into the back side of a cathode ray tube (CRT) 40 to be mounted in the funnel part.
FIG. 14 is a side view, seen from the outside, of a deflection yoke apparatus before winding. FIG. 15 is a sectional view of FIG. 14, wherein a deflection yoke apparatus before the winding of a horizontal deflection coil and a vertical deflection coil is shown.
In FIGS. 14 and 15, the deflection yoke apparatus 30 has an inner bobbin 31 and an outer bobbin 32, which work as a holder to hold a ferrite core 33, a horizontal deflection coil and a vertical deflection coil (not shown). The ferrite core 33 is arranged between the inner bobbin 31 and the outer bobbin 32. The ferrite core 33 is made of a magnetic material. The ferrite core 33 is shaped with its screen side in an expansively opening form. The combined body of the bobbins 31, 32 and the ferrite core 33 is made to form a bell-shape as a whole.
The inner and outer bobbins 31, 32 are made of non-magnetic material such as polypropylene resin. The front side of them (the screen side) is formed in an expansively opening shape. The inner bobbin 31 is designed to have the neck part of a cathode ray tube (CRT) inserted from the expansively opening side, as shown in FIG. 13. And on the inside face of the inner bobbin 31, a pair of vertical deflection coils (not shown) are arranged along the grooves between a plurality of guides 311, being wound to generate a magnetic field in a vertical direction of the CRT screen.
On the outside face of the inner bobbin 31, the ferrite core 33 is arranged, and the outside of the ferrite core 33 is designed to be held down by the outer bobbin 32. The inner bobbin 31 and the outer bobbin 32 are designed to be fastened at the circular screen side base and at the circular neck side base, and the ferrite core 33 is to be placed and held between the inner bobbin 31 and the outer bobbin 32.
On the inner bobbin 31, a plurality of guides 311 are formed to connect each base on the screen side and the neck side. Besides, both ends of said plurality of guides 311 are extended to form a plurality of guide hooks 311a and 311b, the cross section of which is L-shaped (or inverse L-shaped).
Also, along a plurality of grooves (in other words, slits), which are formed between a plurality of guides 311 to connect the screen side base with the neck side base, and at the same time, the electric wire, as a vertical deflection coil, is wound around close to the inside face of the inner bobbin 31 to wind between said plurality of guide hooks 311a and 311b, the cross section of which is L-shaped (or inverse L-shaped). The winding pattern is, as shown in FIG. 16, guided by a plurality of grooves between each of guides 311 to go, as shown by the circled numbers in the figure, like 1.fwdarw.2.fwdarw.3.fwdarw.4.fwdarw.5.fwdarw.6.fwdarw.7.fwdarw.8.fwdarw.9 and so on. Each winding of 2.fwdarw.3.fwdarw.4, 5.fwdarw.6.fwdarw.7.fwdarw.8, 9.fwdarw.10.fwdarw.11.fwdarw.12 and so on is done a plurality of times before goes on to the next groove.
FIG. 17 illustrates a conventional deficiency which arises when winding is done at the D part of FIG. 15. FIG. 18 is a sectional view at the C--C line of FIG. 15.
As shown in FIG. 15, all the plurality of guides 311, which also serve as supports of the inner bobbin 31, are narrow in width as the guides approach the neck side (the upper part of the figure) from the screen side (the lower part of the figure). This is because the groove width between the guides 311 is set to be uniform from screen side to neck side for convenience of winding, and the guide width is forced to be narrowed on the neck side where the diameter of the opening is small.
In conventional structures shown in FIGS. 14 and 15, when an electric wire is wound into the grooves which are formed between the guides 311 of the inner bobbin 31, a bundle of electric wire is aggregated with the narrow guides in between at the neck side where the guide width is narrow and the diameter of the opening is small. As a result, as shown in FIG. 17, the guides 311 are pushed outwardly by the electric wire 34 wound in to cause deformation. Accordingly, the distribution of electric wire slips out from an intended distribution, enlarging the possibility to cause irregularity in the function of a deflection yoke.
In order to prevent the guides from being deformed, conventionally, adhesive 36 is used to fix the clearance between the guide 311 of the inner bobbin 31 and the ferrite core 33, as shown in FIG. 18. This method, however, requires both an additional process to apply the adhesives and additional time for the adhesives to dry completely. This has been an issue in workability and cost.
As stated above, with a conventional deflection yoke apparatus, when electric wire is wound, the way to accumulate it may push guides to cause deformation, change the distribution of winding, and cause a problem of irregularity in the functions of the deflection yoke apparatus. Application of adhesives, as a means to cope with these issues, has imposed this problem in workability and the like.